DE 101 02 028 A1 already discloses a twin clutch transmission, in which the transmission input shaft and the transmission output shaft are arranged coaxially with respect to one another. The countershafts assigned to the two partial transmissions are arranged parallel to one another.
Furthermore, DE 31 31 156 A1 discloses twin clutch transmissions in which a transmission input shaft and a transmission output shaft are arranged coaxially with respect to one another. The twin clutch transmission has a plurality of reverse gears in addition to six forward gears.
DE 103 25 647.4, not yet published, shows a twin clutch transmission, in which, in accordance with the invention:                a transmission input shaft and a transmission output shaft are arranged coaxially with respect to one another,        two countershafts are arranged so as to be offset in parallel with respect to one another and to the transmission input shaft and transmission output shaft,        a direct gear is provided,        otherwise, all the even-numbered forward gears are assigned solely to one countershaft and all the odd-numbered forward gears are assigned solely to the other countershaft,        there being arranged coaxially on the transmission output shaft, offset axially with respect to a shift sleeve assigned to the direct gear and a further forward gear, a further shift sleeve assigned to two forward gears,        there lying, offset axially with respect to said two shift sleeves, a shift sleeve plane, in which are arranged two further shift sleeves, each of which is assigned in each case to one of the two countershafts.        
In contrast to the invention, in this twin clutch transmission, a forward gear runs via four gear ratio stages.